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	$87.46	5.168%	$91.9799	$91.98	$92.00	$92.00
Purchase #2	$33.32	11.196%	$37.0505	$37.05	$37.05	$37.10
Purchase #3	$69.86	3.541%	$72.3337	$72.33	$72.35	$72.30
Purchase #4	$213.40	7.567%	$229.548	$229.55	$229.55	$229.50
Purchase #5	$83.33	10.821%	$92.3471	$92.35	$92.35	$92.30
Purchase #6	$250.76	11.352%	$279.2263	$279.23	$279.25	$279.20
Purchase #7	$224.47	12.103%	$251.6376	$251.64	$251.65	$251.60
7 purchase totals =	$962.60		$1,054.1231	$1,054.13	$1,054.20	$1,054.00