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	$201.67	3.511%	$208.7506	$208.75	$208.75	$208.80
Purchase #2	$100.84	11.623%	$112.5606	$112.56	$112.55	$112.60
Purchase #3	$197.38	3.737%	$204.7561	$204.76	$204.75	$204.80
Purchase #4	$147.83	12.373%	$166.121	$166.12	$166.10	$166.10
Purchase #5	$229.91	3.637%	$238.2718	$238.27	$238.25	$238.30
Purchase #6	$57.27	3.346%	$59.1863	$59.19	$59.20	$59.20
Purchase #7	$80.34	3.678%	$83.2949	$83.29	$83.30	$83.30
7 purchase totals =	$1,015.24		$1,072.9413	$1,072.94	$1,072.90	$1,073.10