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	$223.33	5.646%	$235.9392	$235.94	$235.95	$235.90
Purchase #2	$33.27	13.485%	$37.7565	$37.76	$37.75	$37.80
Purchase #3	$110.54	7.366%	$118.6824	$118.68	$118.70	$118.70
Purchase #4	$67.55	6.426%	$71.8908	$71.89	$71.90	$71.90
Purchase #5	$130.27	5.696%	$137.6902	$137.69	$137.70	$137.70
Purchase #6	$138.65	12.734%	$156.3057	$156.31	$156.30	$156.30
Purchase #7	$24.82	9.751%	$27.2402	$27.24	$27.25	$27.20
7 purchase totals =	$728.43		$785.5050	$785.51	$785.55	$785.50