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	$65.61	11.861%	$73.392	$73.39	$73.40	$73.40
Purchase #2	$170.33	9.768%	$186.9678	$186.97	$186.95	$187.00
Purchase #3	$31.88	10.267%	$35.1531	$35.15	$35.15	$35.20
Purchase #4	$247.49	10.160%	$272.635	$272.64	$272.65	$272.60
Purchase #5	$190.76	10.333%	$210.4712	$210.47	$210.45	$210.50
Purchase #6	$98.41	11.176%	$109.4083	$109.41	$109.40	$109.40
Purchase #7	$250.85	5.498%	$264.6417	$264.64	$264.65	$264.60
7 purchase totals =	$1,055.33		$1,152.6691	$1,152.67	$1,152.65	$1,152.70