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	$185.28	4.408%	$193.4471	$193.45	$193.45	$193.40
Purchase #2	$198.77	11.423%	$221.4755	$221.48	$221.50	$221.50
Purchase #3	$73.56	12.768%	$82.9521	$82.95	$82.95	$83.00
Purchase #4	$59.99	3.164%	$61.8881	$61.89	$61.90	$61.90
Purchase #5	$133.76	9.399%	$146.3321	$146.33	$146.35	$146.30
Purchase #6	$60.34	11.104%	$67.0402	$67.04	$67.05	$67.00
Purchase #7	$230.89	8.510%	$250.5387	$250.54	$250.55	$250.50
7 purchase totals =	$942.59		$1,023.6738	$1,023.68	$1,023.75	$1,023.60