Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$169.77	10.695%	$187.9269	$187.93	$187.95	$187.90
Purchase #2	$43.25	11.704%	$48.312	$48.31	$48.30	$48.30
Purchase #3	$243.31	8.392%	$263.7286	$263.73	$263.75	$263.70
Purchase #4	$152.63	9.868%	$167.6915	$167.69	$167.70	$167.70
Purchase #5	$225.63	12.198%	$253.1523	$253.15	$253.15	$253.20
Purchase #6	$57.91	6.617%	$61.7419	$61.74	$61.75	$61.70
Purchase #7	$38.27	11.677%	$42.7388	$42.74	$42.75	$42.70
7 purchase totals =	$930.77		$1,025.2920	$1,025.29	$1,025.35	$1,025.20