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	$194.61	5.518%	$205.3486	$205.35	$205.35	$205.30
Purchase #2	$169.66	7.741%	$182.7934	$182.79	$182.80	$182.80
Purchase #3	$67.33	8.300%	$72.9184	$72.92	$72.90	$72.90
Purchase #4	$207.74	7.301%	$222.9071	$222.91	$222.90	$222.90
Purchase #5	$169.68	7.362%	$182.1718	$182.17	$182.15	$182.20
Purchase #6	$99.73	9.609%	$109.3131	$109.31	$109.30	$109.30
Purchase #7	$62.75	11.204%	$69.7805	$69.78	$69.80	$69.80
7 purchase totals =	$971.50		$1,045.2329	$1,045.23	$1,045.20	$1,045.20