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	$91.75	4.764%	$96.121	$96.12	$96.10	$96.10
Purchase #2	$203.61	3.824%	$211.396	$211.40	$211.40	$211.40
Purchase #3	$98.81	12.665%	$111.3243	$111.32	$111.30	$111.30
Purchase #4	$57.54	8.873%	$62.6455	$62.65	$62.65	$62.60
Purchase #5	$64.83	3.480%	$67.0861	$67.09	$67.10	$67.10
Purchase #6	$250.44	13.191%	$283.4755	$283.48	$283.50	$283.50
Purchase #7	$112.51	4.786%	$117.8947	$117.89	$117.90	$117.90
7 purchase totals =	$879.49		$949.9431	$949.95	$949.95	$949.90