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	$47.60	12.662%	$53.6271	$53.63	$53.65	$53.60
Purchase #2	$68.65	3.550%	$71.0871	$71.09	$71.10	$71.10
Purchase #3	$94.55	4.709%	$99.0024	$99.00	$99.00	$99.00
Purchase #4	$133.32	5.849%	$141.1179	$141.12	$141.10	$141.10
Purchase #5	$157.41	10.758%	$174.3442	$174.34	$174.35	$174.30
Purchase #6	$237.58	3.159%	$245.0852	$245.09	$245.10	$245.10
Purchase #7	$244.44	12.223%	$274.3179	$274.32	$274.30	$274.30
7 purchase totals =	$983.55		$1,058.5818	$1,058.59	$1,058.60	$1,058.50