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	$186.86	5.774%	$197.6493	$197.65	$197.65	$197.60
Purchase #2	$58.70	6.584%	$62.5648	$62.56	$62.55	$62.60
Purchase #3	$78.28	6.570%	$83.423	$83.42	$83.40	$83.40
Purchase #4	$111.64	5.836%	$118.1553	$118.16	$118.15	$118.20
Purchase #5	$219.82	11.236%	$244.519	$244.52	$244.50	$244.50
Purchase #6	$90.81	5.869%	$96.1396	$96.14	$96.15	$96.10
Purchase #7	$87.76	4.717%	$91.8996	$91.90	$91.90	$91.90
7 purchase totals =	$833.87		$894.3506	$894.35	$894.30	$894.30