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	$200.83	7.647%	$216.1875	$216.19	$216.20	$216.20
Purchase #2	$190.34	11.252%	$211.7571	$211.76	$211.75	$211.80
Purchase #3	$175.44	5.540%	$185.1594	$185.16	$185.15	$185.20
Purchase #4	$92.90	7.180%	$99.5702	$99.57	$99.55	$99.60
Purchase #5	$25.69	7.579%	$27.637	$27.64	$27.65	$27.60
Purchase #6	$84.56	7.706%	$91.0762	$91.08	$91.10	$91.10
Purchase #7	$167.76	10.711%	$185.7288	$185.73	$185.75	$185.70
7 purchase totals =	$937.52		$1,017.1162	$1,017.13	$1,017.15	$1,017.20