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	$58.88	5.812%	$62.3021	$62.30	$62.30	$62.30
Purchase #2	$5.67	11.673%	$6.3319	$6.33	$6.35	$6.30
Purchase #3	$242.67	12.542%	$273.1057	$273.11	$273.10	$273.10
Purchase #4	$234.34	6.821%	$250.3243	$250.32	$250.30	$250.30
Purchase #5	$66.57	6.498%	$70.8957	$70.90	$70.90	$70.90
Purchase #6	$71.90	6.151%	$76.3226	$76.32	$76.30	$76.30
Purchase #7	$249.66	11.441%	$278.2236	$278.22	$278.20	$278.20
7 purchase totals =	$929.69		$1,017.5059	$1,017.50	$1,017.45	$1,017.40