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	$111.39	12.362%	$125.16	$125.16	$125.15	$125.20
Purchase #2	$40.69	7.216%	$43.6262	$43.63	$43.65	$43.60
Purchase #3	$145.96	10.368%	$161.0931	$161.09	$161.10	$161.10
Purchase #4	$209.33	6.790%	$223.5435	$223.54	$223.55	$223.50
Purchase #5	$77.48	6.670%	$82.6479	$82.65	$82.65	$82.60
Purchase #6	$118.69	7.534%	$127.6321	$127.63	$127.65	$127.60
Purchase #7	$171.29	7.455%	$184.0597	$184.06	$184.05	$184.10
7 purchase totals =	$874.83		$947.7625	$947.76	$947.80	$947.70