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	$73.29	5.789%	$77.5328	$77.53	$77.55	$77.50
Purchase #2	$6.61	13.609%	$7.5096	$7.51	$7.50	$7.50
Purchase #3	$200.71	11.376%	$223.5428	$223.54	$223.55	$223.50
Purchase #4	$244.48	8.214%	$264.5616	$264.56	$264.55	$264.60
Purchase #5	$151.77	13.523%	$172.2939	$172.29	$172.30	$172.30
Purchase #6	$88.80	3.316%	$91.7446	$91.74	$91.75	$91.70
Purchase #7	$207.26	9.213%	$226.3549	$226.35	$226.35	$226.40
7 purchase totals =	$972.92		$1,063.5402	$1,063.52	$1,063.55	$1,063.50