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	$188.79	3.422%	$195.2504	$195.25	$195.25	$195.30
Purchase #2	$86.34	4.153%	$89.9257	$89.93	$89.95	$89.90
Purchase #3	$62.47	13.816%	$71.1009	$71.10	$71.10	$71.10
Purchase #4	$169.68	11.215%	$188.7096	$188.71	$188.70	$188.70
Purchase #5	$142.25	12.678%	$160.2845	$160.28	$160.30	$160.30
Purchase #6	$217.82	12.571%	$245.2022	$245.20	$245.20	$245.20
Purchase #7	$47.37	12.574%	$53.3263	$53.33	$53.35	$53.30
7 purchase totals =	$914.72		$1,003.7996	$1,003.80	$1,003.85	$1,003.80