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	$212.33	13.502%	$240.9988	$241.00	$241.00	$241.00
Purchase #2	$71.86	7.453%	$77.2157	$77.22	$77.20	$77.20
Purchase #3	$77.35	7.227%	$82.9401	$82.94	$82.95	$82.90
Purchase #4	$202.27	7.140%	$216.7121	$216.71	$216.70	$216.70
Purchase #5	$41.66	4.275%	$43.441	$43.44	$43.45	$43.40
Purchase #6	$51.89	3.845%	$53.8852	$53.89	$53.90	$53.90
Purchase #7	$191.72	10.548%	$211.9426	$211.94	$211.95	$211.90
7 purchase totals =	$849.08		$927.1355	$927.14	$927.15	$927.00