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	$165.81	4.743%	$173.6744	$173.67	$173.65	$173.70
Purchase #2	$210.29	4.392%	$219.5259	$219.53	$219.55	$219.50
Purchase #3	$41.62	5.337%	$43.8413	$43.84	$43.85	$43.80
Purchase #4	$98.31	4.275%	$102.5128	$102.51	$102.50	$102.50
Purchase #5	$210.79	4.231%	$219.7085	$219.71	$219.70	$219.70
Purchase #6	$105.94	11.532%	$118.157	$118.16	$118.15	$118.20
Purchase #7	$168.29	8.668%	$182.8774	$182.88	$182.90	$182.90
7 purchase totals =	$1,001.05		$1,060.2973	$1,060.30	$1,060.30	$1,060.30