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	$208.58	4.650%	$218.279	$218.28	$218.30	$218.30
Purchase #2	$224.31	11.555%	$250.229	$250.23	$250.25	$250.20
Purchase #3	$111.73	6.243%	$118.7053	$118.71	$118.70	$118.70
Purchase #4	$171.25	4.731%	$179.3518	$179.35	$179.35	$179.40
Purchase #5	$217.53	9.639%	$238.4977	$238.50	$238.50	$238.50
Purchase #6	$108.25	5.444%	$114.1431	$114.14	$114.15	$114.10
Purchase #7	$30.68	7.653%	$33.0279	$33.03	$33.05	$33.00
7 purchase totals =	$1,072.33		$1,152.2338	$1,152.24	$1,152.30	$1,152.20