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	$130.50	11.172%	$145.0795	$145.08	$145.10	$145.10
Purchase #2	$68.45	11.133%	$76.0705	$76.07	$76.05	$76.10
Purchase #3	$89.28	11.208%	$99.2865	$99.29	$99.30	$99.30
Purchase #4	$26.45	4.227%	$27.568	$27.57	$27.55	$27.60
Purchase #5	$68.40	4.208%	$71.2783	$71.28	$71.30	$71.30
Purchase #6	$96.61	10.251%	$106.5135	$106.51	$106.50	$106.50
Purchase #7	$187.67	11.332%	$208.9368	$208.94	$208.95	$208.90
7 purchase totals =	$667.36		$734.7331	$734.74	$734.75	$734.80