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	$197.29	5.675%	$208.4862	$208.49	$208.50	$208.50
Purchase #2	$120.73	10.229%	$133.0795	$133.08	$133.10	$133.10
Purchase #3	$64.45	11.303%	$71.7348	$71.73	$71.75	$71.70
Purchase #4	$124.61	11.729%	$139.2255	$139.23	$139.25	$139.20
Purchase #5	$211.66	5.804%	$223.9447	$223.94	$223.95	$223.90
Purchase #6	$153.63	13.754%	$174.7603	$174.76	$174.75	$174.80
Purchase #7	$191.35	11.648%	$213.6384	$213.64	$213.65	$213.60
7 purchase totals =	$1,063.72		$1,164.8694	$1,164.87	$1,164.95	$1,164.80