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	$212.27	4.327%	$221.4549	$221.45	$221.45	$221.50
Purchase #2	$206.63	7.168%	$221.4412	$221.44	$221.45	$221.40
Purchase #3	$116.34	12.407%	$130.7743	$130.77	$130.75	$130.80
Purchase #4	$136.55	8.498%	$148.154	$148.15	$148.15	$148.20
Purchase #5	$53.71	4.649%	$56.207	$56.21	$56.20	$56.20
Purchase #6	$31.69	5.825%	$33.5359	$33.54	$33.55	$33.50
Purchase #7	$241.76	3.778%	$250.8937	$250.89	$250.90	$250.90
7 purchase totals =	$998.95		$1,062.4610	$1,062.45	$1,062.45	$1,062.50