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	$152.73	7.582%	$164.31	$164.31	$164.30	$164.30
Purchase #2	$74.54	3.790%	$77.3651	$77.37	$77.35	$77.40
Purchase #3	$35.37	3.386%	$36.5676	$36.57	$36.55	$36.60
Purchase #4	$198.92	5.103%	$209.0709	$209.07	$209.05	$209.10
Purchase #5	$177.56	4.410%	$185.3904	$185.39	$185.40	$185.40
Purchase #6	$102.59	3.260%	$105.9344	$105.93	$105.95	$105.90
Purchase #7	$225.69	6.580%	$240.5404	$240.54	$240.55	$240.50
7 purchase totals =	$967.40		$1,019.1788	$1,019.18	$1,019.15	$1,019.20